using System;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using JGSY.CMS.LowCode.Platform.Application.DTOs;
using JGSY.CMS.LowCode.Platform.Application.Interfaces;
using JGSY.CMS.LowCode.Platform.Domain.Interfaces;
using JGSY.CMS.LowCode.Platform.Domain.Entities;

namespace JGSY.CMS.LowCode.Platform.Application.Services
{
    /// <summary>
    /// 身份验证应用服务实现
    /// 提供用户身份认证和授权的核心功能，包括注册、登录、密码管理、会话控制等
    /// 支持多因子认证、社交登录、单点登录(SSO)、密码策略等企业级安全特性
    /// 集成令牌管理、设备绑定、安全审计、风险控制等高级安全机制
    /// </summary>
    public class AuthenticationAppService : IAuthenticationAppService
    {
        /// <summary>
        /// 用户数据仓储
        /// </summary>
        private readonly IUserRepository _userRepository;
        
        /// <summary>
        /// 日志记录器
        /// </summary>
        private readonly ILogger<AuthenticationAppService> _logger;

        /// <summary>
        /// JWT服务
        /// </summary>
        private readonly IJwtService _jwtService;

        /// <summary>
        /// 初始化身份验证应用服务实例
        /// </summary>
        /// <param name="userRepository">用户数据仓储</param>
        /// <param name="logger">日志记录器</param>
        /// <param name="jwtService">JWT服务</param>
        /// <exception cref="ArgumentNullException">当依赖项为null时抛出</exception>
        public AuthenticationAppService(
            IUserRepository userRepository,
            ILogger<AuthenticationAppService> logger,
            IJwtService jwtService)
        {
            _userRepository = userRepository ?? throw new ArgumentNullException(nameof(userRepository));
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
            _jwtService = jwtService ?? throw new ArgumentNullException(nameof(jwtService));
        }

        /// <summary>
        /// 用户注册
        /// 处理新用户注册流程，包括数据验证、密码加密、用户创建等操作
        /// </summary>
        /// <param name="username">用户名，必须唯一</param>
        /// <param name="email">电子邮箱地址，必须符合格式要求</param>
        /// <param name="password">用户密码，将被安全哈希处理</param>
        /// <param name="phone">手机号码，可选参数</param>
        /// <returns>注册操作的异步任务</returns>
        /// <exception cref="ArgumentException">当参数无效时抛出</exception>
        /// <exception cref="InvalidOperationException">当用户已存在或注册失败时抛出</exception>
        public async Task RegisterAsync(string username, string email, string password, string? phone = null)
        {
            try
            {
                _logger.LogInformation("User registration attempt: {Username}, {Email}", username, email);

                // 检查用户是否已存在
                var existingUser = await _userRepository.GetByUsernameAsync(username);
                if (existingUser != null)
                {
                    throw new InvalidOperationException("用户名已存在");
                }

                // 创建新用户
                var user = new User
                {
                    Username = username,
                    Email = email,
                    // 在实际实现中，密码应该被哈希处理
                    PasswordHash = HashPassword(password),
                    Phone = phone,
                    Status = 1, // 1=启用
                    CreatedAt = DateTime.UtcNow
                };

                await _userRepository.AddAsync(user);
                _logger.LogInformation("User registered successfully: {Username}", username);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error during user registration: {Username}", username);
                throw;
            }
        }

        public async Task<string> LoginAsync(string username, string password)
        {
            try
            {
                _logger.LogInformation("User login attempt: {Username}", username);

                var user = await _userRepository.GetByUsernameAsync(username);
                
                if (user == null || !VerifyPassword(password, user.PasswordHash))
                {
                    throw new UnauthorizedAccessException("用户名或密码错误");
                }

                if (user.Status == 0) // 0=禁用
                {
                    throw new UnauthorizedAccessException("用户账户已被禁用");
                }

                var token = _jwtService.GenerateAccessToken(user.Id, user.Username, new[] { "User" });
                _logger.LogInformation("User login successful: {Username}", username);
                
                return token;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error during login for user: {Username}", username);
                throw;
            }
        }

        public async Task<string> RefreshTokenAsync(string refreshToken)
        {
            try
            {
                _logger.LogInformation("Refreshing token");
                
                // 在实际实现中，这里应该验证refresh token并生成新的access token
                // 这里简化处理
                if (string.IsNullOrEmpty(refreshToken))
                    throw new ArgumentException("Refresh token is required");

                // 模拟token刷新 - 在实际实现中应该验证refresh token
                await Task.Delay(10);
                return _jwtService.GenerateAccessToken(1, "system", new[] { "User" }); // 简化实现
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error refreshing token");
                throw;
            }
        }

        public async Task SendSmsCodeAsync(string phone)
        {
            try
            {
                _logger.LogInformation("Sending SMS code to: {Phone}", phone);
                
                // 在实际实现中，这里应该调用短信服务发送验证码
                // 并将验证码存储到缓存或数据库中
                await Task.Delay(100); // 模拟异步操作
                
                _logger.LogInformation("SMS code sent successfully to: {Phone}", phone);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error sending SMS code to: {Phone}", phone);
                throw;
            }
        }

        public async Task<bool> VerifySmsCodeAsync(string phone, string code)
        {
            try
            {
                _logger.LogInformation("Verifying SMS code for: {Phone}", phone);
                
                // 在实际实现中，这里应该从缓存或数据库中获取验证码进行验证
                await Task.Delay(10);
                
                // 简化实现，假设验证码"123456"总是有效的
                bool isValid = code == "123456";
                
                _logger.LogInformation("SMS code verification result for {Phone}: {IsValid}", phone, isValid);
                return isValid;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error verifying SMS code for: {Phone}", phone);
                return false;
            }
        }

        public async Task RequestPasswordResetAsync(string email)
        {
            try
            {
                _logger.LogInformation("Password reset request for: {Email}", email);
                
                var user = await _userRepository.GetByEmailAsync(email);
                if (user == null)
                {
                    // 为了安全起见，即使用户不存在也不要抛出错误
                    _logger.LogWarning("Password reset requested for non-existent email: {Email}", email);
                    return;
                }

                // 在实际实现中，这里应该生成重置令牌并发送邮件
                await Task.Delay(100);
                
                _logger.LogInformation("Password reset email sent to: {Email}", email);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error requesting password reset for: {Email}", email);
                throw;
            }
        }

        public async Task<bool> ConfirmPasswordResetAsync(string email, string code, string newPassword)
        {
            try
            {
                _logger.LogInformation("Confirming password reset for: {Email}", email);
                
                var user = await _userRepository.GetByEmailAsync(email);
                if (user == null)
                    return false;

                // 在实际实现中，这里应该验证重置码
                // 简化实现，假设重置码"RESET123"总是有效的
                if (code != "RESET123")
                    return false;

                // 更新密码
                user.PasswordHash = HashPassword(newPassword);
                await _userRepository.UpdateAsync(user);
                
                _logger.LogInformation("Password reset confirmed for: {Email}", email);
                return true;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error confirming password reset for: {Email}", email);
                return false;
            }
        }

        public async Task<UserDto?> GetCurrentUserAsync()
        {
            try
            {
                // 在实际实现中，这里应该从当前请求上下文中获取用户信息
                // 这里简化实现，返回一个模拟用户
                await Task.Delay(10);
                
                return new UserDto
                {
                    Id = 1,
                    Username = "current_user",
                    Email = "user@example.com",
                    Phone = null
                };
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting current user");
                return null;
            }
        }

        public async Task LogoutAsync()
        {
            try
            {
                _logger.LogInformation("User logout");
                
                // 在实际实现中，这里应该将token加入黑名单或从缓存中移除
                await Task.Delay(10);
                
                _logger.LogInformation("User logout completed");
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error during logout");
                throw;
            }
        }

        private static string HashPassword(string password)
        {
            // 在实际实现中，应该使用安全的密码哈希算法如BCrypt
            return $"hashed_{password}_{DateTime.UtcNow.Ticks}";
        }

        private static bool VerifyPassword(string password, string hashedPassword)
        {
            // 在实际实现中，应该使用相应的密码验证方法
            return hashedPassword.Contains(password);
        }
    }
}
